Effect of early BCG formation on tidal bar formation in clusters

Determine how the formation and efficiency of bars in cluster galaxies would change if the brightest cluster galaxy (BCG) formed earlier such that member galaxies interacted with a single central massive galaxy rather than multiple massive progenitors of the BCG.

Background

This study analyzes 15 bar-like galaxies in the most massive TNG50 cluster and finds that 11 bars were tidally induced or strongly enhanced by interactions with massive progenitors of the brightest cluster galaxy (BCG). Many bar formation events occurred before the BCG was fully assembled, and several galaxies interacted with multiple BCG progenitors.

Because the BCG formed through mergers during the period when bars were forming, the galaxies experienced a complex sequence of interactions. The author notes that this coevolution complicates assessments of bar formation efficiency and raises the unresolved question of how outcomes would differ in a simpler configuration where the BCG had formed earlier and interactions occurred with a single central galaxy.

References

The significance of this complicated scenario and its implications for the efficiency of bar formation in clusters deserve further study. It remains unclear what would happen if the configuration were simpler, that is, if the BCG formed earlier and the other galaxies interacted with a single object rather than several of its massive progenitors.

— Diverse lifestyles of bar-like galaxies and their coevolution with the brightest galaxy in the most massive cluster of TNG50  (2604.01758 - Lokas, 2 Apr 2026) in Section 4 (Discussion), final paragraph